1. Field of the Invention
The present invention relates to a timepiece such as a wristwatch in which a panel for electricity generation or light emission is provided in a module displaying a time or the like and the panel is covered with a display plate. Particularly, the present invention relates to a timepiece in which an attachment configuration of the display plate is improved.
2. Description of the Related Art
A timepiece is known as a related art in which a panel including a solar cell or an electroluminescence and a light-transmissive display plate covering the same are disposed on the module (for example, see Japanese Patent No. 4398555 (Patent Document 1)).
In the related art, an auxiliary ring formed of a resin molding product has a pair of cylindrical projection portions in a plurality of locations on an upper surface of an outer peripheral portion thereof, respectively, and has a projection on a lower surface thereof. The projections of the auxiliary ring are engaged with the module, and the auxiliary ring is fixed to the module. With this, the display plate is formed in a thin plate shape by a synthetic resin such as a transparent acrylic resin or a polycarbonate resin, and has a plurality of notches in a peripheral portion thereof. By engaging the notches with the cylindrical projection portions of the module, the display plate is fixed to the auxiliary ring.
Specifically, the pair of cylindrical projection portions has a gap therebetween and is formed so as to be elastically deformable toward the gap. The notches of the display plate elastically deform a pair of cylindrical projection portions placed inside thereof in a direction approaching each other and are engaged with them. As a result, it is possible to fix the display plate in the state in which a lateral deviation or rotation is prevented.
In a timepiece according to the related art, a diameter of the cylindrical projection portion is not changed from a root thereof to a tip thereof, and the holding of the display plate to the auxiliary ring only depends on an engagement force that acts from the cylindrical projection portion to an edge of the notch in a horizontal direction (a lateral direction).
By such engagement force, warping based on the plurality of notches is easily generated in the display plate having relatively low strength, whereby a distortion is generated in the display plate. Since an occurrence of the distortion degrades the quality of the timepiece, an improvement thereof is desired.
Furthermore, an assembly including an auxiliary ring and a display plate attached thereto as mentioned above is moved toward the incorporation until being incorporated to a timepiece exterior assembly after integration of the assembly, and thus, the assembly receives the vibration or the like at that time. For that reason, in the configuration of the related art mentioned above in which the display plate is held only by the horizontal engagement force with the cylindrical projection portion, the display plate is moved upward and floats owing to the vibration or the like, such a situation further progresses and the display plate may deviate.
As mentioned above, in the timepiece of the related art, there is a problem in that the display plate is liable to be attached in a distorted manner, and, until the auxiliary ring and the display plate attached thereto are incorporated to the timepiece exterior assembly, the display plate floats or deviates with respect to the ring member.